An artist's conception of Nanuqsaurus hoglundi, a pgymy tyrannosaur that lived in the Arctic 70 million years ago.

Tiny T. Rex Relative Roamed a Warmer Arctic

A miniature cousin of Tyrannosaurus rex once roamed the Arctic, a new fossil discovery reveals.

The new tyrannosaur (Nanuqsaurus hoglundi) had a skull length of between 23 and 27 inches (60 to 70 centimeters) when full-grown. In comparison, an adult T. rex boasted a skull about 60 inches (150 cm) long — that's a whopping 5 feet (1.5 meters).

Karen Carr

An artist's conception of Nanuqsaurus hoglundi, a pgymy tyrannosaur that lived in the Arctic 70 million years ago.

"The 'pygmy tyrannosaur' alone is really cool because it tells us something about what the environment was like in the ancient Arctic," study researcher Anthony Fiorillo of the Perot Museum of Nature and Science in Dallas, said. "But what makes this discovery even more exciting is that Nanuqsaurus hoglundi also tells us about the biological richness of the ancient polar world during a time when the Earth was very warm compared to today."

Teeny tyrannosaurThe identification of the new species comes from a few skull bone fragments found in 2006 on Alaska's North Slope, at the Kikak-Tegoseak Quarry inland from Prudhoe Bay. Originally, paleontologists thought the bones belonged to another tyrannosaurid dinosaur, Gorgosaurus libratus. But further research showed the fossil to be about 70 million years old, which matched better with the timing and range of a close relative of Gorgosaurus, Albertosaurus sarcophagus.

On closer inspection, the skull fragments didn't match the Albertosaurus, either. In fact, the bones appear to fill evolutionary and geographical gaps between other tyrannosaur species, the researchers reported March 12 in the journal PLOS ONE.

The first word of the scientific name given to the new species means "polar bear lizard," and the second is in honor of earth scientist Forrest Hoglund. The fossil discovery came from northern Alaska, perhaps highlighting the adaptability of this toothy predator. [In Photos: A Near-Complete T. Rex Skeleton]